To meet Federal Motor Vehicle Safety Standards, a vehicle may include an upper anchor attachment to receive a child safety seat tether hook connected to an upper portion of the child safety seat back. The connection of the upper portion of the child safety seat to the vehicle may reduce the forward movement of the child safety seat during a frontal crash. However, the shock applied by child safety seat restraining equipment to the child safety seat occupant may increase in the case of a forward vehicle collision.
One approach to reduce the impact of the collision force to the child safety seat is described in the U.S. Pat. No. 6,767,057. In particular, anchor attachments to the child safety seat with energy absorbing mechanisms are disclosed. In one example, the upper anchorage assembly includes a steel U-shaped bracket with a first end secured to the vehicle horizontally and a second end having a latchable portion for releasable engagement with the corresponding upper child seat latch. If the predetermined forward force is exceeded, the U-shaped bracket bends forward and is deformed. The deformation of the bracket absorbs energy.
However, the inventors herein have recognized disadvantages with such an energy absorbing device. Specifically, the steel, U-shaped bracket may not maintain desired loads under a range of impact energy to the child safety seat. For example, small deformation or no deformation may be desired for the anchor attachment under low impact force so that the child safety seat can be kept in position. In some situations, it may be desired to have constant deformation or constant load exerting to the child safety seat under a certain range of impact energy. However, the steel, U-shaped bracket described in the U.S. Pat. No. 6,767,057 cannot achieve the above objectives.